title: Total synthesis of hygrolines and pseudohygrolines.
abstract: A concise two-step synthesis of all four diastereoisomeric hygrolines ((-)-hygroline (1), (+)-hygroline (2), (-)-pseudohygroline (3), (+)-pseudohygroline (4)) has been developed based on the (-)-sparteine (5)- or (+)-sparteine surrogate 11-mediated enantioselective lithiation of N-Boc pyrrolidine (6), followed by reaction of the chiral anion with (S)- or (R)-propylene oxide. Reduction of the resulting N-Boc amino alcohols furnished hygrolines and pseudohygrolines in 30% to 56% overall yields with dr's > 95:5.
authors.affiliation: ETH Zürich , Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, HCI H405, Wolfgang-Pauli Str. 10, CH-8093 Zürich, Switzerland.
authors.forename: Marc
authors.initials: M
authors.lastname: Liniger
authors.forename: Katja
authors.initials: K
authors.lastname: Estermann
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Altmann
mesh_terms: D008094:Lithium / Q000737:chemistry*; D015394:Molecular Structure; D011759:Pyrrolidines / Q000138:chemical synthesis* / Q000737:chemistry*; D013034:Sparteine / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: C531441:N-Boc-pyrrolidine; D011759:Pyrrolidines; C000588747:pseudohygroline; D013034:Sparteine; D008094:Lithium